Hybrid batteries typically use several cells of different chemistries connected together by one or more electrical switches. By combining cells of different chemistries, these hybrid batteries aim to provide benefits that would otherwise be impossible with only one type of cell. For example, a primary battery with a relatively large energy density may be combined with a secondary battery that has a relatively low energy density, but is rechargeable. However, the battery chemistries are typically not compatible with each other, and thus require separate physical containers for each cell. This separate housing adds bulk to the overall structure, and some battery chemistries, such as lithium-ion, may require additional puncture-resistant protection surrounding each cell due to their volatility when exposed to oxygen. Furthermore, electrical switches and connections between individual cells may add resistance, and therefore losses in efficiency, to the overall battery.